6ABC News: "Since the first of the year, legislation that would ban or restrict the undercover taping on farms has been introduced in nine states and remains active in six of those: Nebraska, Indiana, Arkansas, Pennsylvania, Tennessee and California. Hearings on the bills were held this week in three of those states.

WATCH ABC News 'Nightline' Tonight at 12:35 a.m. EST for the full story from Investigative Correspondent Brian Ross.

Should it pass the state House, the Indiana law would make it illegal to take photos or video at an agricultural facility without the consent of the owner. The bill had its first reading in the state House of Representatives this week.

In Arkansas, pending legislation would make it a crime for anyone other than law enforcement personnel to investigate or collect evidence of animal cruelty.

The laws come in the wake of a series of undercover camera exposes that have led to a public outrage and calls for reform on large-scale, so-called "factory farms."

Last year ABC News reported that Mercy for Animals, which has shot undercover footage at chicken, turkey, pig and dairy farms around the country, had joined with 26 other groups, including the ASPCA and the Humane Society of the U.S., to oppose such laws. A statement from the coalition called the "ag gag" bills "a wholesale assault on many fundamental values" and a threat to health, safety and freedom of the press.

An ABC News investigation that aired in November 2010 showed video recorded by a Mercy for Animals activist who worked undercover at one of the nation's largest egg producers, Sparboe Farms, located in Iowa. Wearing a hidden camera, he recorded unsanitary conditions and repeated acts of cruelty on chickens.

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After the investigation, which aired on "20/20" and "World News with Diane Sawyer," Sparboe's major customers – McDonald's and Target – cancelled contracts with the egg producer. Several grocery chains followed suit and the Food and Drug Administration launched an investigation into conditions found there.

Letter to

First Lady of the United StatesMichelle Obama

EVERY "STATE HOUSE" of every state in the United States

state House of Representatives of every US state

and 6 others

U.S. House of Representatives

U.S. Senate

Pennsylvania State House

Pennsylvania State Senate

President of the United States

Pennsylvania Governor

Overturn and stop legislation banning video in factory farms from being passed!